Dauter et al. Can anomalous signal of sulfur become a tool for solving protein crystal structures?
J Mol Biol (1999) vol. 289 (1) pp. 83-92
In MAD work with selenium precautions are taken to ensure the highest possible accuracy of the measured intensities. Crystals are often aligned to measure the Bijvoet-related reflections on the same exposure or inverse beam technique utilized to record Friedel mates close in time, to make sure that the measurements of both mates, F+ and F-, are done with similar paths of the X-ray beams in the crystal, so as to minimize the systematic errors in the estimation of Delta-F-anom.